i really don't like differing your raise sizing due to the cards your being dealt.. you can get away with it at $3 level but i wouldnt advise it. i think 3x is fine.i think you played it pretty well considering, the flop bet is smallish, i like the pot control on the turn, if he was drawing you get to the river cheap, since its a blank you could easily be inducing a bluff here.. so i would make the call also, think you played it fine
If you start to raise differing sizes due to the cards your getting, you ARE giving way to much info to players who are observant.. like i said $3 you may get away with it.
but in general as the blinds go up, the raise sizing goes down, thats due to stack sizes and saving the extra $$ when you get 3bet all in..
early levels i will raise more like 3.5x, but its due to everyone being relatively deep stacked. The only time i would raise differing sizes is due to how i see my opponants, if i think they are strong players i may raise more, as i dont want to get in a hand postflop against them, the weaker they are, the more comfortable i am with playing postflop so ill raise smaller, but its nothing to do with my cards..